Safety slow-down and stop motion for electric elevators.



\ D. LARSON.

SAFETY SLOW DOWN AND STOP MOTION FOR ELECTRIC ELEVATORS.

APPLIGATIOK FILED JULY 5, 1910.

Patented A ris, 1913.

5 Woe W501 UNITED STATES PATENT OFFICE.

DAVID LARSON, OF YONKERS, NEW YORK, ASSIGNOR TO OTIS ELEVATOR COMPANY,OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SAEETY SLOW-DOWN AND STOP MOTION FOR ELECTRIC ELEVATORS.

Specification of Letters Patent.

Patented Apr. 8, 1913.

Application filed July 5, 1910. Serial No. 570,257.

To all whom it may concern:

Be it known that I, DAVID LARSON, a subject of theKing of .Sweden,residing at Yonkers, in the county of Westchester and State of New York,have invented a new and useful Improvement in Safety Slow-Down and StopMotions for Electric Elevators, of which the following is aspecification.

My invention relates to an elevator slowdown device which is adapted tobe used in connection with electric elevators.

One (if the objects of my invention is to provide means for slowing downthe elevator motor at any desired place or places.

Another object is to provide adjustable electro responsive meansforeffecting the slow-down action at any desired speed of the motor.

Other objects will appear hereinafter, the novel combinations being setforth in the appended claims.

In the accompanying drawing my invention is diagrammatically shown asemployed in connection with an electric elevator.

Broadly speaking my invention is to pre vent the elevator car fromtraveling at excessive speed at any point or points, and especially ator near the limits of travel of v the car. If the speed is not too highwhen the slow-down positions are reached, the slow-down apparatus willnot be required, and will not be operated. I

Referring to the drawing, the motor M operates the car C and thecounterweight W by means of the cable 13 which passes about the tractiondrums 11 and 12. Current is supplied .to the armature of the motor Mthrough the main switch S, potential switch P main conductors 14, 15,reversing switch R or R, st-artingresistance X, motor leads 16, 17, andto the winding of the brake B by the operation of the car controllerswitch K. The starting resistance X is controlled by the acceleratingmagnet A and the circuitof the magnet winding has the hatchway switches18 and .19 connected in series with it. Both the accelerating magnetwinding and the brake magnet winding receive current through theauxiliary reversing switch contacts 1 or r. A cam 20 on the elevator caris adapted to engage the slow-down switches 18 and 19, and the limitswitches 21 and 22. The potential switch winding is connected in serieswith the normally closed limit switches 21 and 22. A hand lever H iscommonly provided manually to open the potential switch. The motor fieldis connected by the conductors 23 and 24 to the main conductors 14-15.

Connected to the motor leads 16 and 17 are the .conductors 25 and 26.Conductor 25 leads through the resistance Y to contact 27, and conductor26 is connected to contact 28, so that when the contacts 27 and 28 arejoined, a circuit whichincludes the resistance Y is closed in parallelwith the motor armature, or in other words forms a shunt circuit for thearmature. The magnet 29 is operative when energized to join the contacts27 and 28. The terminals of this magnet winding 29 are connected byconductors 33 and 34 to the contacts 31 and 32, and the first namedterminal also has a connection by way of resistance 36, conductor 35, tothe slow-down hatchway switches 36 and 37. These switches 36 and 37 arenormally open and are adapted to be closed by a grooved projection 38carried by the car, and when closed at the same time the controllerswitch K is in an operating position, complete a circuit from the mainconductor 14 through the switch K and byway of conductor 39 or 40andslow-down switch 36 or 37 to the conductor 35 and through resistance36 to one terminal of the said magnet winding 29. Contact 32 isconnected by means of conductor 41 to the other main conductor 15, sothat when the two contacts 31 and 32 are joined at the time one of thehatchway switches 36 or 37 and the controller switch circuited and theresistance 36 prevents a short-circuit connection between the mainconductors 14 and 15. \Vhen, however, the contacts 31 and 32 areseparated, a circuit is closed from one main to the other through themagnet winding 29, which causes the switch contacts 27 and 28 to beunited and the shunt resistance Y to be inserted in parallel with themotor M. The contacts 31 and 32 are separated when the magnet E isoperatively energized, and the magnet winding 30 is subject to thepotential of the motor armature by reason of its connections throughconductors 43 and 26 to the motor lead 17 and through conductor 42 tomotor lead 16. When the potential across the motor armature is of aprescribed value the that is, it will be operatively energized at anygiven speed of the motor.

' In order that my invention may be more readily understood, let it beassumed that the hand lever in the car 0 is turned to the right toenergize reversing switch R and cause the motor to lower the car. Theaccelerating magnet A is energized and the resistance X isshort-circuited. As the car nears a predetermined point, such as thelimit of travel of the car, the cam 20 engages the hatchway switch 19and opens the circuit of the accelerating magnet winding, causing theresistance X to be inserted in the motor armature circuit. As the carcontinues, the grooved projection 38 closes the slow down hatchwayswitch 37 and if the speed of the motor is sulficiently high the magnetE is energized, causing the magnet winding 29 to receive an energ1zingcurrent and to close the shunt circuit through the resistance Y1 Thisexerts a powerful braking effect upon the motor, reducing the speed sothat the car is not traveling at too great a speed when the cam 20 opensthe limit switch 22, breaking the energizing circuit through thepotential switch winding. If the speed of the car and the motor is nottoo great at the time the switch 37 is closed the slow down shunt willnot be necessary and the magnet E is not energized. In this respect theaction is entirely relative and automatic.

Although I have thus set forth the preferred embodiment of my invention,it is evident that those skilled in the arts to which this appertainsmay make various changes without departingfrom the spirit and scope ofthe invention.

What I claim and desire to secure by Letters Patent of the United Statesis 1. In an electric safety for elevators, the combination of a motor, acar, an electro-responsive means dependent upon the speed of the motorfor energization, and operative only when the s eed of the motor isabove a predetermined value and at a predetermined point or points inthe travel of the car to establish a dynamic circuit and thereby effectthe slowing down of the motor-before the elevator car reaches eitherlimit of travel.

2. In an electric safety for elevators, the combmation of a motor, anelevator car, and electroresponsive means dependent upon thecounter-electro-motive force of the motor for energization and operativeonly when the car is at a predetermined point in its travel to establisha dynamic brake circuit and thereby slow down the car and the motor whenthe speed thereof is too high.

3. In'an electric safety for elevators, the combination of a motor, anelevator car, resistance for a shunt circuit, means for closing the saidcircuit parallel to the motor armature, a magnet dependent forenergization upon the counter-electromotive force of the motor, andmeans cooperating with said magnet and operative to effect the operationof the said circuit closing means only asthe elevator car approacheseither limit of travel.

4. In an electric safety for elevators, the combination of a motor,resistance for a motor shunt circuit, means operative only atpredetermined points in the operation of the elevator for closing thesaid circuit, and a magnet dependent for energization upon'thc speed ofthe motor and operative to effect the energization of the circuitclosing means only when the speed of the motor is too great at saidpredetermined points.

5. In an electric safety for elevators, the combination of a motor,switches in the elevator hatchway closed by the car, resistance for amotor shunt circuit, means for closing the circuit and a magnet subjectto the same potential as the motor armature energized when the motorattains a predetermined speed and effective to operate the circuitclosing means when the speed of the elevator car is too great at thetime a switch is closed by the car.

6. In an electric safety for elevators, the

combination of a motor, resistance for a motor shunt circuit, a switchto close the said circuit, a magnet normally open circuited for closingthe switch when energized, hatchway switches closed by the elevator car,and an adjustable magnet connected to the motor armature terminals andoperative to direct an energizing current to the other magnet when thespeed of the motor is too high at the time a hatchway switch is closed.

7 In elevator safety apparatus, the combination of a car, a motor,hatchway slow down switches normally open, means in conjunction with thecar for closing the switches, resistance for a circuit arallel with themotor armature, a magnet or closing the said circuit parallel with thearmature, and an adjustable magnet energized when the speed of the motorreaches a predetermined limit and operative when energized at the time ahatchway switch is closed to direct an energizing current through theother magnet to elfect the slowing down of the motor.

8. In elevator safety apparatus, the combination of a car, a motor,hatchway switches normally open, means in connection with the car forclosing the switches, resistance for a motor armature shunt circuit,

a magnet to close the said circuit, a short circuit comprising a switchconnected across the winding of said magnet, an adjustable ma etconnected across the motor armature an operative when energized to opensaid short circuit switch and direct acurrent through the other magnetwhen one of the hatchway switches is closed, and resistance in serieswith the circuit closing magnet winding. i

9. In elevator safety apparatus, the combination of a car, a motor,hatchway switches normally open', means in connection with the car forclosing the switches, resistance for a motor armature shunt circuit, amagnet to close the said circuit, a switch normally closed toshort-circuit the said magnet winding and operative to energize the saidmagnet when opened at the time one of the hatchway switches is closed,resistance to prevent a short-circuit when one of hatchway switches .isclosed when the last named switch is closed and in circuit with themagnet winding when the switch is open, and an electro-magnet connectedacross the motor armature and operative when energized to open thenormally closed switch.

10. In. an electric elevator, the combination of a motor, reversingswitches for the motor, a controlling switch in the elevator car,normally open hatchway switches closed by the car, resistance for amotor armature shunt circuit, a magnet operative when energized to closethe said clrcuit, the magnet winding being in circuit which includes ahatchway switch and the controlling switch when the latter is in anoperating position, and a magnet connected across the motor armatureoperative when energized to direct current through the other magnetwinding.

11. In elevator safety apparatus, the combination of a mot-or, reversinswitches for the motor, a car controller switch, normally open hatchwayswitches closed by the car, a motor accelerating magnet, hatchwayswitches normally closed in series therewith, resistance for a motorarmature shunt,

means in connection with the car for opening the closed switches todeenergize the motor accelerating magnet, and means to close a shuntcircuit includin the said resistance when the speed of t e car is toogreat at the time the hatchway switches are opened by the car.

12. The combination in an elevator, of a motor, a car, retardingmechanism for the motor, means to automatically efi'ect the operation ofsaid retarding mechanism when the car reaches a predetermined point inits travel, and mechanism to prevent the operation of saidretarding)mechanism while the speed of the motor is elow a predeterminedvalue.

13. In an elevator, a -motor, a car, a dynamic brake circuit for themotor, mechan1sm operated by a moving part of the elevator to cause thesaid brake circuit to be established, and means controlled by the speedof the motor to prevent the said clrouit from being established.

' In testimony whereof, I have signed my name to this specification inthe presence of two subscribing witnesses.

- DAVID LARSON.

Witnesses:

EDWARD I-I. STEELE, GEORGE D. Ross.

